Meckel's diverticulum is a cause of significant morbidity and mortality. Often this is related to the delay in diagnosis. Based on a US population of 200 million people and a 2% incidence, there are 4 million Meckel's diverticula present waiting to cause symptoms. Considering that most Meckel's diverticula are asymptomatic and that many authors have described the condition as a great mimic, the diagnosis is often quite elusive. Therefore, a high index of suspicion is needed to diagnose Meckel's diverticulum correctly and expeditiously as the source of disease in the patient with an often unclear abdominal presentation. The difficulty with diagnosis should be lessened if one considers that Meckel's diverticulum presents largely in the male and younger age groups with the three major symptom complexes of bowel obstruction, gastrointestinal bleeding, and inflammation. Use of 99mTc pertechnetate scintigraphy appears to be the diagnostic study of choice if Meckel's diverticulum is suspected and the patient is clinically stable. When one considers the potential for bad outcome if Meckel's diverticulum is missed in the setting of possible obstruction or hemorrhage (i.e., bowel infarction or exsanguination), a high index of suspicion and diagnostic aggressiveness is warranted. Lastly, if one thought is to be left behind, it should be: "Meckel's is a great mimic that must be considered in all cases of intra-abdominal disease in which the cause is not readily apparent."